Mechanism for varying the speed of hydraulic press rams



Oct. 14, 1941. w, gfi s 2,258,886

I MECHANISM FOR VARYING THE SPEED OF HYDRAULIC PRESS RAMS Filed July 21,1.938 3 Sheets-Sheet l Oct. 14, 1941.

w. ERNST MECHANISM FOR VARYING THE SPEED OF HYDRAULIC PRESS RAMS s Sheets-Sheet 2 Filed. July 21, 1938 Wm an 6 mm A mm mm m& .i. 3 I g 8 w U8E w mm Patented Get. 14, 194i MECHANISM FOR VARYING THE SPEED OFHYDRAULIG PRESS RAMS Walter ma, Mount Gilead, om, assignor to TheHydraulic Development Corp. Ina, Wilmington, Deh, a corporation ofDelaware Application July 21, 1938, Serial No. 220,554 9, (llaims. (Cl.60-52) This invention relates to hydraulic machine.

control systems, and in particular, to systems in cluding a hydraulicpump andhaving provision for altering the delivery of the pump to varythe speed of the machine at different points in its operation One objectof this invention is to provide means responsive to the motion of ahydraulic machine for varying the delivery of a hydraulic pumpso as tocause the machine to slow down at a predetermined point in itsoperation. I 1

Another object is toprovide means, as described above, wherein themachine is thereafter caused to gain speed-again following the slowingdown thereof. v

Another objectis to provide a hydraulic press control system operated bya hydraulic pump, and including means responsive to the arrival of thepress platen at a predetermined point to cause the platen to slow downimmediately prior to its engaging the workpiece, and thereafter to gainspeed so as to apply an increased pressing force control system, asdescribed in the preceding paragraph, wherein the press is operated by avariable delivery pump having a flow-control of the pump, and preferablyalso to cause the link to resume its original-position afterthe platenhas passed the above-mentioned predetermined point.

Another object is to provide a hydraulic press control system, as abovedescribed, wherein a time delay device in the system Operates to .causean increase of flow of pressurefluid from the pump to the press apredetermined time afterthe reduction of flow from the pump to thepress.

This application is a continuation in part of my copending application,Ser. No. 128,827, filed March 3, 1937.

In the drawings: a

Figure 1 is a diagrammatic view, partly broken away. of the essentialportions of a hydraulic press circuit with a pneumatic collapsible linkinterposed between the press control rod and th servomotor control ofthe pump.

Figure 2 is an enlarged central longitudinal section through thepneumatic collapsible link of Figure l, with the link parts in oneposition.

Figure 3 is a view similar to Figure 2, but with the link parts in areversed position relatively to Figure 2.

Figure 4 is a diagrammatic view of a hydraulic press control systemhaving an electrically oper- General arrangement In general, thehydraulic press control system of this invention consists of a hydraulicpress to which pressure fluid is supplied by a variable de-' livery pumphaving a. flow-control element for varying its delivery. Interposedbetween the manually controlled lever or control rod of the pressand-the servomotor valve rod forvcontrolling the delivery' of the pump,is a collapsible or expansible link operated either pneumatically orelectrically when the press platen reaches a predetermined position uponits stroke. When this position is reached the link is operated to permitthe shifting of the servomotor valve rod so as to shift the pumpflow-control member and reduce the. nelivery of the pump. A time delaydevice,

suchas a dash-pot; is optionally provided for establishing atime delayperiod for the operation under reduced flow so that the pump resumes itsnormal or increased flow at the end of a predetermined time intervalfollowing its reduction of flow. The link device may beeitherpneumatically or electrically operated, and both such systems areillustrated herein. The link may also be expansible or collapsible,according to the. me-

' chanical requirements of its particular position in advisable toincrease the speeds of hydraulic the pump operating mechanism, ashereinafter presses far beyond the speeds previously thought necessary.When such presses are used'in connection with dies, however, it has beenfound that the life of the dies is greatly shortened and damagefrequently caused thereto because of the considerable shock which is setup when the press platen engages the dies while moving 'at this highspeed. The purpose of the present invention, therefore, is to enable thepress platen to close the dies at a high speed so as to shorten theworking cycle, yet to slow down the platen just before the dies areengaged, whereupon the dies are engaged smoothly and without seriousshock,

Pneumatic collapsible link system Referring to the drawings in detail,Figure 1 shows a reversible variable'delivery pump I having fluidconnections II and I2, connected to conduits i3 and I4, respectively.-Depending upon whether the pump is in a forward or reverse position, oneof the conduits II or H serves as a pressure conduit while the otherserves as a suctionconduit. The conduit ljserves as a pressure conduitfor supplying pressure fluid to the main cylinder of the press duringthe pressing stroke, while the conduit l4 serves as a suction conduit towithdraw fluid from the return side. of the press-operating circuit, ina manner well known to those skilled in the art.

Fluid for operating the circuit is'contained in the surge tank IS. Thepump it is provided on -tor I1 is, in turn, controlled by the servomotorvalve rod 18. The details of the pump I and its associated elements formno part of the present invention, and a disclosure thereof "is found inmy copending application, Ser. No. 170,250, filed October 21, 1937.

The pump I4 is mounted upon a bracket i4 secured to the press head 20,which in turn, is connected to the press bed 2| by the strain rods 22having the nuts 23 threaded upon the ends thereof. The press headcontains a main cylinder (not shown) within which a main plunger 24reciprocates. Secured to the main plunger 24 is a platen 26 having anarm 26 extending laterally aasasso upon the opposite end or the linkdevice 49 is a yoke 52 ivotally connected, as at 53, to the lever 54.The latter is pivotally connected, as at 55,

to the servomotor valve rod i8 oi. the pump II and is pivotally mounted,as at 56, upon the floating link 51, which in turn, is pivotallymounted, as at 54, upon the casing of the servomotor l1.

Connected to the link device 48 is a flexible compressed air conduit l0,connected in turn, to a conduit 40 which leads to a two-way. air releasevalve having a valve rod 42 operated by an arm 43 carrying a roller 84.The valve rod 42 is urged by an internal spring into a normally closedposition. The valve rod 2 is adapted to be moved to the left into anopen position to release air from the valve II by the engagement of theroller 4 with the cam '8 upon the cam arm 44, secured as at 41 to theplaten 2|. The cam 44 is provided with oppositely beveled portions 44and 40 for engaging the valve-operating .roller 64. Mountedeat anhater-mediate point along the conduit 84 is a T-connection I0 having aconduit 'll leading thereto, and containing a choke valve 12. On theopposite side of the choke valve 12 the conduit. ll leads to a source ofcompressed air. such asa tank served by a compressed air pump.

The link device 44, shown in Figures 2 and 3, consists ofia cylinder 14terminating at one end in the yoke 42, as previously explained. Withinthe cylinder 14 is a cylinder bore ll, having ports 16 and 11communicatingtherewith at opposite ends thereof. Only one o! the ports14 or 11 is utilized at a given time, the other being opened to theatmosphere, depending upon whether the link device 4! is to be used fora collapsible or expansible link. The cylinder 14 is provided with pipeconnections 14 and 14 leading to the ports I6 and I1, and serving asconnections for the flexible conduit 49.

Reciprocably mounted within the cylinder bore I! is a piston head 40,mounted as at Ii upon therefrom to encircle the press control rod 21, l

and to engage an adjustable collar 28 thereon collar 32 arranged tooperate a limit switch 34 in the electrical circuit for controlling thereversal of the press circuit in full automatic operation.

The control rod 21 also is provided with a 'collar 34 engagable .by theyoked end 45 of a rocker arm 46, pivotally -moimted upon the rockershaft 31 which, in turn, is mounted upon the press head 24. Pivotallyconnected, as at 34, to the opposite end of the rocker arm' 38 is-aconnecting rod 3! having its lower end pivotally connected, as at 44, tothe armature 4i of the operating solenoid 42. Also pivotally connectedto the rocker arm 34, as at 43, is alink 44 pivotally connected at 7 45to abellcrank 46, the other end of which is pivotally connected at 41 tothe clevis 48 of a linkdevice, generally designated 49, hereinafter.described in more detail. The bellcrank 4B is pivotally mounted, as at50, upon the bracket the threaded end 82 of the piston rod 04. Thelatter is connected, as at 84, to the clevis 48 and locked,in positionby the .locknut-lfi. The piston rod 83 passes through the cylinder head85, secured as at 81, to the cylinder 14. The cylinder head 46 containsa bore 84 with a packing 4!, which is held in place by a gland 9|threaded therein as at II. The cylinder 14 and cylinder head 4' areprovided, respectively, with annular abutments 92 and 92, adapted toengage and limit the stroke of the piston head at the opposite ends ofits stroke.

' and as soon as pressure is removed from the pipe connection II by theopening of the valve 6|, the device will expand intothe position shownin Figure 2, the expansion being accomplished by a spring IIa engagingthe servomotor valve rod l8 within the servomotor II. On the other hand,if the compressed air conduit 54 is connected. to the pipe connectionIt, the link device 4! will be held in the expanded condition shown inFigure 2. and will becollapsed as soon as pressure is removed from thepipe connection 18 and conduit I by the opening of the valve 4 I.

In Figure 1 the link device 419 is in tension when the solenoid 42 isenersized'because the latter,

through the linkage, tends to pull the piston rod 83 and clevis 4b tothe left while the'spring IIa Si mounted upon the press head Ill.Mounted servomotor valve rod I8 to the left, thereby urging the oppositeend of the lever 54 and the yoke 52 to the right. This arrangementprovides a contracted link which is permitted to expand by the releaseof the compressedair from the port I6 and conduit 59. If, however, thelink device 49 were connected directly to the servomotor valve rod I8,the conduit 59 would be connected to the pipe connection I9 in order toaccomplish the same result. The link device 49, under these conditions,would be in compression rather than in tension under the samecircumstances. It is, therefore, an advantage to have the link device 49adapted to be arranged either as a collapsible or expansible link so asto operate either in tension or in compression, as desired, dependingupon the manner in which it is installed.

Operation In the operation of the system shown in Figure 1, let it beassumed that the press platen 25 and main plunger 24 are in theirretracted positions so that the platen is up instead of being down, asshown in Figure l. The compressed air reaching the link device 49,through the conduits 13, II,

the now contracted link device 49, to the servomotor valve rod I8,shifting the servomotor I'I into a position to cause the pump III to.deliver pressure fluid through the line I3, into the upper end of themain cylinder. This causes the main plunger 24 and platen 25-to descendrapidly, aided by gravity and a surge valve (not shown), which for atime permits fluid to enter the main cylinstrikes the roller 84 andshifts the arm 63 to move the valve rod 8|. from the conduits 59 and 69and from the port 15 in the cylinder I4 of the link device 49, so thatthe deviceis now free to expand. The spring IIa that is within theservomotor II is then free to shift the servomotor valve rod I8, therebycausing the shiftring or flow-control member of the pump to be shiftednearly to its neutral position. The stroke of the piston 80 is such thatthe servomotor valve rod I8 cannot cause the shiftring' or pumpflow-control member to be pulled quite to its neutral position. However,because the pump The air then escapes its full stroke position for fulldelivery, the

workpiece or dies have been engaged. The operby the pump I8 from theretraction area of the press, which is relatively small in comparisonwith the advancing area upon the main plunger 24. 1

After the workpiece or dies are engaged, the platen 25 will-no longerdescend by gravity, but is urged in a forward direction to continue itsworking stroke by pressure fluid delivered by the pump I8 through theconduit i3 to the main cylinder against the platen-advancing side of themain plunger 24. As'this area is considerably greater than theretraction area, the platen 25 moves more slowly than it did during theidle advance stroke, even though the pump capacity is the same as it wasbefore the brief period during which its delivery was reduced by theaction of the link device 49, as explained above.

Electrically operated link device and circuit In the modifiedarrangement shown in Figures 4 and 5, the pneumatic link device 49 isreplaced by an electrically operated device 5. Thelatter consists of asolenoid II6 having a winding II'I connected to the lines H8 and H9,running to the power lines I28 and I2I, respectively. Inserted in theline I I9 is a normally closed switch I22 having a switch arm I23,adapted to be operated by a bellcrank I24 pivoted, as at I25, and

having an operating roller I26 adapted to be engaged by the cam5operated by the platen 25.

The switch I22 contains a spring constantly urging the lever 123 intothe position shown in Figure 4. The bellcrank I24 also engages theoperating rod I21 of a time delay device I28, having an adjustment screwI29. Th time delay device I28 may consist of a dash-pot and theadjustment screw I29 a needle valve. Reciproca- 'ble within the solenoidbore I3I is a solenoid exception that a time delay device, such as a'dash-pot I32, is interposed between the solenoid flow-control 'memberhas been pulled nearly to its neutral position, the pump I 8 is capableonly of removing oil slowly from the retraction chamber of the press.This causes the platen 25 to slow down materially for a time.

As soon as the cam 85 passes the roller 54, however, the lever 63 isreturned by springs to its normal position, thereby permitting the valverod 82 of the air release valve BI to return to its normally closedposition. The valve 8! then closes. but the choke I2 prevents the rapidrefilling of the'cylinder I4 of the link device 49 with compressed air.The duration of this time delay can be adjusted by adjusting the choke12. As"

the slowing up of the platen 25 is timed to occur just before the platen25 engages the workpiece I or dies, by the time the link device 49 isrestored to its original position and the servomotor valve rod I8isshifted to cause the pump III to resume plunger I38, and the solenoidwinding III. This dash-pot is provided with an adjusting screw I33 sothat the relative motion between the parts is delayed when the solenoidis energized. An ordinary switch I22 is employed without the time .delaydevice or dash-pot I28 in this arrangement.

The solenoid winding I I1 is connected atone end to the yoke I34, whichin turn. is connected to" .-the servomotor valve lever 54, in the manner(Figure 4) at I35 to a hand lever I36, adjustable relatively to'a sectorplate I31, and pivotally mounted at its lower end upon-a bracket I38,asatl39.-v

The operation of the lectrical circuit shown in Figures 4 and 5 issimilar to that already described for the pneumatic link device 49,shown in Figure l. The solenoid H5 is'normally enerto be attracted bythe solenoid plunger I30, so that the solenoid bore I3I is drawn overthe plunger I30. In this normally energized position, therefore, thesolenoid winding Ill and the plunger I30 are. drawn together in a manneranalogous to the position of the pneumatically operated parts in Figure3. Under these conditions, the solenoid lit when energized acts as arigid contracted link between the hand lever I36 or bellcrank IB- andthe servomotor valve rod I8. When, therefore, the hand lever' I36 or thebellcrank 46 is moved to the left to place the pump I upon its fulldelivery forward stroke, the servomotor valve rod I8 is shifted so thatthe pump I0 withdraws fluid from the retraction side of the presscircuit at a rapid rate, so that the platen 25 moves downward at fullspeed.

When the cam 65 engages the roller I25, however, the bellcrank I24 ismoved, shifting the switch a'rm I23 so as to open the normally closedswitch I22. The solenoid winding II! is thereby deenergized, whereuponthe spring I'Ia within the servomotor II shifts the servomotor valve rodI8 so as to correspondingly shift the flowcontrol element of thevariable delivery pump III almost to its neutral delivery position. Theflow is thereby' so greatly reduced, in a manner similar to that alreadydescribed for the pneumatic control system of Figure 1, as to cause theplaten 25to move downwardly at a reduced speed.

Meanwhile, the dash-pot I28 has come into action, and after the cam 65has passed the roller I28 the bellcrank I24 is prevented from releasingthe switch arm 'I23 by;this dash-pot I28. The latter delaysciosingoftlie switch I22 for a sufflcient period to maintain thesolenoid IIS deenergized, and the pumpgl'lil is kept on reduced strokefor-a predetermined period. At the end of this period, and when thedash-pot I2l has operated to a suiflcient extent, the bellcrank I24releases the switch arm I23, and the consequent 0105 8 0! the switch I22reenergizes the solenoid II. Accordingly, the parts thereof again cometogether, shifting the servomotor valve rod I8 and the shiitring orflow-control member of the pump 10' again to their full deliverypositions. This places the pump III again upon its full forward strokeposition. The press platen 2I then picks up its speed and-resumes itsnormal speed for the completion of the'stroke.

It will be understood that I desire to compre-' hend within my inventionsuch modifications as come within the scope of the claims.

Having thus fully described my invention, what I claim as new and desireto secure by Letters Patent is:

1. In a hydraulic machine control circuit, a

- pump, a hydraulic ram, means for causing said pump to move said ram,saidmeans comprising" a fluid flow-controlling member'ior controllingthe fluid flow from said pump and an operated devicefor initiating amovement of said flow- ,aasasse i 'a fluid flow-controlling member forcontrolling the fluid flow from said pump and a regulating device forregulating the setting oi! said flowcontrolling member, electricallyoperable means associated with said. regulating device and saidflow-controlling member and adapted to cause movement of saidflow-controlling member in one direction, spring means associated withsaid regulating device andurging said flow-controlling member in theopposite direction, means responsive to a predetermined travel of saidram for causing a. shifting of said flow-controlling member to alter thespeed of travel of said ram beyond said predetermined travel, and meansresponsive to a further predetermined travel of said ram in the samedirection for causing said electrically operable means to move in adirection adapted to restore said fluid flow-controlling member to itsoriginal position. a

3. In a hydraulic machine control circuit, a pump, a hydraulic ram,means for causing said pump to move said ram comprising a fluidflowcontrolling device for controlling the ,fluid flow from said pumpand a regulating device for shifting said flow-controlling device,electrically operable means interposed between said regulating deviceand said flow-controlling device and adapted whenenergized to move saidflow-controlling device so as to increase the fluid flow from said pump,means urging said flow controlling member into the opposite direction todeactuated means for restoringthe original condition of energization tosaid electrically operable means.

4. In a hydraulic machine control circuit, a

' pump, a hydraulic ram, means for causing said controlling member to apredetermined position and for holding said member in that position.

electric means associated with said device and adapted when energized tocause movement ;oi

. said flow-controlling member in one direction in response to theoperation of said device, means "responsive toa predetermined travel oisaid ram for effecting deenergiaation of said electric Q means, andmeans responsive to the de-energiza- .ti'on of said electric means tocause movement of said flow-controlling member in another.direcpumpto'move said ram comprising a fluid flow controlling device forcontrolling the fluid flow from said pump and a regulating device forshiit- .ing said flow-controlling device, an electricalsolenoidinterposed between said regulating device and saidflow-controlling device and adapted to effect movement of saidflow-controlling device inone direction; the armature of said solenoidbeing connected to one of said devicesand the coil thereofto the otherdevice, spring means associated with said fluid flow-controlling deviceand adapted to cause movement or said flowcontrolling device in anotherdirection and means responsive to the motion of said rm to apredetermined position for altering the energization oi said solenoid-sothat movement of said flow-controlling device relatively to saidregulating device occurs.

5. In a hydraulic machine control circuit, "I.

- pump, a hydraulic ram, means for causing said tionto temporarily sl wdown the speed of travel :6

pump to move said ram comprising a fluid flowcontrolling device [orcontrolling the fluid flow from said pump and a regulating device forshirting said flow-controlling device, an electrical solenoid interposedbetween said regulating device and saidflow-controlling device-andadapted to effect movement of said flow-controlling device in onedirection, the armature of said solenoid being connected to one ofsaiddevices and the coil thereof to the other device, spring meansassociated with said fluid flow-controlling device and adapted to causemovement of said flow-controlling-devicein another direction, meansresponsive to the motion of said ram to a predetermined position foraltering'the energization of said solenoid so that movement of saidflow-controlling device relatively to said regulating device occurs, andtime delay means responsive to the expiration of a predetermined periodof time after said alteration of the energization of said solenoid forrestoring the original condition of energization to said solenoid.

6. Ina hydraulic machine control circuit, a variable delivery pumphaving a delivery-varying device associated therewith for varying thedelivery thereof, a hydraulic ram, means for causing said pump to movesaid ram, said means comprising a regulating device for shifting saiddelivery-varying device, an expansible and col-' lapsible linkinterposedbetween said device, electric means operatively connected withsaid link and adapted when energized to effect collapse of said link formoving said delivery-varying device into one direction, spring meanscontinuously urging said delivery-varying device into the oppositedirection, and means responsive to a predetermined position of said ramfor temporarily de-energizing said electric means to allow said springmeans to eifect movement of said deliveryvarying device 'while the ramis continuing its movement in the same direction.

'7. In a hydraulic machine control circuit, a variable delivery pumphaving a delivery-varying device associated therewith for varying thedelivery thereof, a hydraulic ram, means for causing said pump to movesaid ram comprising a regulating device for shifting saiddelivery-varying device, an electrically actuated expansible andcollapsible link interposed between said devices, electric meansassociated with said link and adapted when energized to efiect collapsethereof, spring means adapted to bring about an expansion of said linkwhen said electric means isdeenergized, means responsive to the motionof said ram to a predetermined position for deenergizing said electricmeans, and time delay means responsive to the expiration of apredetermined period of time after said de-energization of said electricmeans for restoring the original condition of energization' thereto.

' 8. In a hydraulic machine control circuit, a pump, a hydraulic ram,means for causing said pump to-move said ram, said means comprising aflow-controlling member for controlling the fluid flow from said pumpand a regulating device forregulating the setting of said flowcontrolling member, electric means, said electric means including tworelatively movable parts,

one connected to said flow-controlling member.

and the other connected to said regulating device, said electric meansadapted when energized to cause movement of said flow-controllingmember'in one direction, biasing means responsive to the deenergizationof said electric meansto cause movement of said flow-controlling memberin the opposite direction, and means responsive to the movementof saidram to a predetermined position on its working stroke to de-energize'said electric means whereby the biasing means moves the flow controlmember to temporarily slow down the speed of travel of said ram beyondsaid predetermined travel without changing. the direction of travel.

9. In a. hydraulic machine control circuit, a

pump, a hydraulic ram, means for causing said pump to move said ram,said means comprising a ber in the opposite direction, and meansresponsive to. the movement of said ram to a predetermined position onits working stroke to dc-energize said electric means whereby thebiasing means moves the flow control member to temporarily slow down'thespeed of travel of said ram beyond said predetermined travel withoutchanging the direction of travel, and 'timedelay means responsive to theexpiration of a predetermined period of time after the operation of saidbiasing means, for restoring the original condition of energization ofsaid electric means.

WALTER ERNST.

